What happens when you drop a Slinky? The answer, in this video, may surprise you.
And when you attach a tennis ball to the bottom?
The Slinky, like Silly Putty, was an accident: the spring was originally intended to support naval instruments. The Ur-Slinky was accidentally dropped, “walked” down several objects, and the rest is history.
h/t: Science Goddess and Ed Yong via Matthew Cobb